In conventional multi-channel audio coding, possible coding schemes include discrete multi-channel coding or parametric coding such as MPEG Surround. The scheme used depends on the bandwidth of the audio system. Parametric coding methods are known to be scalable and efficient in terms of listening quality, which makes them particularly attractive in low bitrate applications. In high bitrate applications, the discrete multi-channel coding is often used. The existing distribution or processing formats and the associated coding techniques may be improved from the point of view of their bandwidth efficiency, especially in applications with a bitrate in between the low bitrate and the high bitrate.
U.S. Pat. No. 7,292,901 (Kroon et al.) relates to a hybrid coding method wherein a hybrid audio signal is formed from at least one downmixed spectral component and at least one unmixed spectral component. The method presented in that application may increase the capacity of an application having a certain bitrate, but further improvements may be needed to further increase the efficiency of an audio processing system.
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